Strain tomography via neutron Bragg edge imaging on similar and dissimilar Eurofer97 joints

Nuclear fusion is a potential source of electricity which can address the environmental problems posed by fossil fuels. Eurofer97 steel is a primary structural material for breeding blanket and divertor components in fusion Tokamaks. Assembling and maintaining the structural integrity of these in-vessel components requires joining techniques, forming similar and dissimilar Eurofer97 joints and inducing immersive residual stress. The interaction of the residual strain and the heterogeneous microstructure degrades the mechanical performance of fusion components. However, inspecting bulk residual stress distribution, which is desirable for visualising the local stress distribution interior of the material, is still lacking. This study aims to achieve bulk residual strain inspection for the laser-welded Eurofer97 similar joint and brazed W/Eurofer97 dissimilar joints using strain tomography and (ii) further develop the strain reconstruction technique via neutron Bragg edge imaging by combination with a finite element model. The 3D strain distribution obtained from reconstruction will be correlated with the microstructure and local mechanical properties. The results obtained from the current study will enhance the design protocols and structural integrity assessment of the EU DEMO and UK STEP (Spherical Tokamak for Energy Production) fusion power plants.